51) The stimuli for contraction of the heart come from : 1380957.
51) The stimuli for contraction of the heart come from within the heart rather than from the nervous system.
52) The left ventricle pumps blood into the pulmonary artery.
53) Inflammation is a typical part of the initial process that can result in a heart attack.
54) Blockage of the aorta is the most common fatal heart attack.
55) Some proteins are too large to leave the capillaries.
56) Valves in veins are important features that help keep blood moving back toward the heart.
57) Capillaries are essentially water-tight vessels, so nutrients and gases diffuse in and out, but water stays put.
58) The trachea branches into left and right bronchioles.
59) When the thoracic cavity gets smaller, the pressure inside the lungs increases.
60) Contraction of the diaphragm causes exhalation to occur.
61) Pulmonary ventilation occurs because of pressure differences between the lungs and the external environment.
51) The stimuli for contraction of the heart come from : 1380957